/sci/ - Science & Math

>>11717786
Spheres don't have cores.

>>11717786
>and if it's spherical what would be at its core?

>>11717792
For you

>>11717792
>>11717799
What's this?

>>11717823
a 2-d representation of a 3-d object

>>11717786
Last time I checked (yesterday), it was huge.
So it's huge shaped.

Yes, /sci/ deserves this kind of posts.

>>11717823
it's a sphere which is a boundary of the solid disc embedded in R3. not every sphere is a priori a boundary of a solid disc embedded in R3.

>>11717786
I think it's an expanding surface of a 4-Torus (basically space invaders world but in 3d). It just seems like the most intuitive answer to me since it doesn't need to deal with the problems of a boundary.

I don't see why there should be anything special at the central point. It would be nice to have for a universal empire since it would be closest to all other stars (probably), but I don't see why it should have any special astrological properties

>>11717792
retard

>>11717958
define the core of a sphere. now.

>>11717786
Our universe is not sphere because it has infinite size.

>>11718161
>it has infinite size.
how do you know ?

>>11717983
The core of a sphere is that point which has the same distance to all points of the sphere, also called its center.
I thought you passed high school?

>>11718275
this is a property of an embedding of the sphere into a larger space, not the sphere itself
the universe (or any space for that matter) can be spherical without existing in a larger universe
learn differential geometry

>>11718323
Oh, so you mean a 4-Sphere with the universe as its surface? That'd be a weird twist of the 4-Torus idea I mentioned earlier, and it also makes sense. Then the question about its center really becomes pointless since that position in space doesn't exist, but still the "center" wouldn't be a very special point

>>11717823
An embedding of a 2d sphere into 3d Euclidean space. With that embedding, you can define a center. That isn't an inherent property of spheres though and would require a spherical universe to be embedded in a larger geometric structure to make sense of OP's question.
>>11717958
Not an argument.

>>11718546
It would be a 3-sphere. What you're calling a sphere is a ball, which has a sphere at its surface. In 3 dimensions, a 3-ball has a 2-sphere at its surface.

>>11718546
a circle can be realized as [0,1] with endpoints glued together
a 2-sphere can be realized as the unit 2-disc with its boundary circle collapsed to a point (picture)
a 3-sphere can be realized as the unit 3-disc with its boundary collapsed to a point

you can picture 3-torus as a cube where passing through the boundary moves you to the opposite side.
3-sphere is similar, but you can walk through the boundary and appear anywhere on the boundary you like. because the whole boundary is a single point now.

explosion cloud of smoke moving away from center of mass in ??? direction shaped

>>11719104
how long really is the universe can we use smoking weed to predict the formations in objects

>>11719104
>>11719132
its filling empty space- if there was nothing there it wouldn't be there.
or there are giant aliens.

>>11719147
>giant aliens
ah,.. God...

>>11719274
so the universe is haped like its expanding at a rate relative to its' resistance to expanding or god isnt real and it can go on forever (annd is shaped like smoke) it is also shaped like the map of neurons in a brain or the internet interestingly enough. maybe we are inside a computer chip or network (but not ai or simulation)

>>11719331

>>11718323
Hmm, interesting. You're saying that we couldn't find center of a sphere using FFF? I'll have a think about this

>>11718989
Naughty picture!

>>11719592
Imagine living on a sphere. How would you find the center of a sphere if the sphere itself is all there is?

>>11719606
Using second fundamental form, I presume. I've forgotten most of differential geometry and need to revise it, but you could find a point at which SFF is ill defined

>>11719651
The second fundamental form is only defined when there is an embedding.

>>11717786
Universe is flat as far as we can tell. If it was a sphere, it would be the point of big bang in spacetime

>>11719651
second fundamental form is not defined for a space, only for an embedding of a space
and assuming our sphere is the usual sphere in R3, the center isn't even a point on the surface. how the hell do you want to find it using only the geometry of the surface ?

>>11719710
>>11719928
That's true. My initial thought process was that if we could define a plane curve, and then find normal variations of it, at some point we would have a vanishing SFF, but I see the issue now. As I've mentioned, I'm rusty, need to revise

>>11717786
its a torus

>>11717786
>and if it's spherical what would be at its core?
your momas black ass nigga

>>11719827
>spacetime
things move in space in time spacetime is bullshit

so core of the universe = big bang, so now there is a massive black hole at the center of the universe?

>>11717786
non-euclidean geometry is heresy. BURN HIM AT STEAK. Op uses space time and magic! Hail Euclid, hail the right angle.

>>11720403
how did you come up with that? what part of explosion = black hole at center of universe? what if god was smoking a big doob and his breath has bacteria in? when did the universe start then?

>>11718648
Oh, sorry, thanks for the correction Anon

>>11718989
>you can appear anywhere on the boundary you'd like
This isn't practically true. If we look at the 2-sphere again, we could make the same argument, however looking how sphere actually looks, at which angle you will exit the boundary is clearly obvious - on the opposite side of the boundary (so that the line is straight in the sphere).

>>11722052
2-sphere is 2-disc with its boundary circle collapsed to a single point. center of the disc is the south pole and the boundaryi is the north pole. going to the boundary means going to the north pole from where you can exit in whatever direction meaning you reappear anywhere on the boundary.
3-sphere it's the same.

>>11722167
Then it's not equivalent to a sphere. On a sphere, going over a pole is clearly defined.

>>11717786
Probably a hypersphere.

>>11722632
lol disc modulo boundary is a sphere, open literally any book on topology or something
the boundary is single point now !! so going into boundary, walking around boundary, exiting boundary is the equivalent of going to the north pole, waiting at north pole for a while, exiting north pole in a different direction that you came from

>>11722632
I'VE EVEN MADE A PICTURE

>>11723352
Alright I'm a fucking retard, for some reason I thought we were talking about straight lines in which case (d) would make no sense. Gotta kms now

Either sphere is wrong or dark matter/energy is wrong.

>>11717786
hyperbolic geometry is pretty kino, pic related was a homework problem in my diff geo class to find the area of an ideal triangle on a surface with gaussian curvature K = -1.

The fractional linear transforms between the disk and the upper half plane are also quite nice, makes for a very aesthetic link between complex analysis and geometry.

>>11723352
An n-disc is not an n-sphere... you need two coordinate charts to make this work.

Is this trying to represent a stereographic projection? If so, you are missing the North pole, and you need to repeat this process from the top in order to obtain a smooth surface (that is the sphere). Keep in mind that your n-disk is open, which is why the pole isn't covered by one chart. There is no smooth coordinate chart mapping an n-disk to an n-sphere, you need two at best.

>>11718161
why do you think this?
how old are you?
do you even know what infinite means?
do you even know what the universe is?

>>11723998
>An n-disc is not an n-sphere
n-disc modulo boundary is n-sphere, read the whole discussion

>>11717786
>universe is flat
>tfw flat earthers were right all along

>>11724199
>show up at flat earth conference
>earth has 0 curvature
>I actually mean the curvature of space near earth
>everyone gets confused because I actually know physics
>they still want to agree with me
>mfw

The universe itself doesn't exist. The only thing there is, is perception and consciousness, so this entire rambling about the topology of the universe is utterly delusional. But muh neighbourhood and manifold, muh density parameter.

>>11717786
This.

It's spherical, know why? Because every shape that can exist can be created within a sphere.

This whole torus idea is laughable because they are describing the 'spheres' we see like the earth which they fail to see as a donut because the 'hole' in the centre isn't big enough. All of them have an 'entry' point and an 'exit' point.

Life is about idea, stories and gullible fools who believe others instead of creating their own, both ignorant scientists and the ignorant faithful. To create is to suffer and none of us want to do that so we adhere to somebody elses poorly crafted story instead. Happily ignorant (though educated) in a box somebody else made.

We could have lived an easy and heavenly life on earth if the world wasn't filled with dullards who refuse to suffer to create.

>>11717786
Spherical with the most massive black hole at the center

>>11718161
A sphere is the only representation of the infinite we have, it 'eats' its own 'tail' so to speak.

>>11718231

Anon doesn't know

>>11726340
>Because every shape that can exist can be created within a sphere.
and how do you define "a shape that can exist" ? let me guess. it's a shape that can be created within a sphere.

>>11726368
Create a shape that wont fit within a sphere.

Technically its a 'fluid sphere' but really only in simplification terms for an audience. If you have a creative mind you understand that it is all undefined created by undefined parts that are their own whole too.

A 'sphere' is just the simplest representation of it we have the capacity to measure without being more fluid with our definitions which is I think an oxymoron. You want me to define the undefinable.

That's the simplest explanation you will probably ever get that can contain within it an infinite amount of complexities.

>>11726393
>Create a shape that wont fit within a sphere.
klein bottle

>>11726393
Actually let me do one better, maybe.

Every shape we have is a representation of a circle and the shape we define as a circle is still only a representatino of a circle. It is not a circle because it is not a 'perfect' circle. This implies an infinite representation of form, a spiral, so to speak.

The centre of that spiral being a 'dot', a 'circle' or a form in and of itself. You now have a beginning, an end and an in-between. Past, present and future but clearly none of these DEFINED terms are true in the absolute sense because an infinite form or spiral implies no beginning or end. It's all relative but its all the same.

An infinite amount of forms within an infinite amount of forms. Like russian stacking dolls that get smaller only to get bigger and house the one that 'started' the set.

>>11726401

You are literally retarded.

>>11726412
I'm literally right

>>11726368
>>11726401
Stop replying to schizos, as you can see you will just motivate them to shit up the thread even more

>>11719576
this picture looks like one of my boxers after a long day of working

>>11717786
Toroidal sphere
I have no conclusive evidence for this but my gut feeling

>>11718323
why would you use a linebreak to end a sentence when you could just use a period? i suppose the next thing you say will be that you have a genius-level iq

>>11717786
>and if it's spherical what would be at its core?
it's a 3D version of the surface of a sphere you moron